The Distribution of HoS in the Lake of Faro 



201 



PH 

 8,20H 



8,00 

 7,80 



7,60H 

 7,1,0 

 7,20 

 7,00 



6,80- 



RED 



WATER / 



/ 



.<;-"'-■ 



IV 



VI 



IX 



I960 



VII VIII 



MONTHS 

 Fig. 6. Variations of pH at station A. 



XI XII 



1961 



collected at a depth of 25 m and in the mud taken at bottom at 

 station A, the bacteria counted were respectively in the order 

 of 10^ per liter of water and of 10^ per kg of mud. 



The bacteriological test of the Winogradsky cultures- aquar- 

 ium showed the presence of Thiopolycoccus ruber colonies and, 

 in a lesser quantity, of fomis belonging to the genera Cromatium 

 and Thiocystis. 



DISCUSSION 



The occuiTence of "red water" had previously been observed 

 by several authors in the MeditciTanean brackish waters. Cerruti 

 (3) reported that in August 1938 the water of Mar Piccolo, in 

 Taranto, took on a deep dark-reddish colour, and he connected 

 this phenomenon with contemporarv presence of hydrogen sul- 

 phide at a depth of 12.5 m. In 1953 Cviic encountered such 



